1. Field of the Invention
The present invention relates to an ocular lens material. More particularly, it relates to an ocular lens material which has high oxygen permeability and high mechanical strength and is excellent also in deposit resistance and which is thus useful for e.g. contact lenses, intraocular lenses or artificial cornea.
1. Discussion of Background
Heretofore, as ocular lens materials, particularly as materials for hard contact lenses, those made of copolymers of e.g. siloxanyl methacrylate or fluoroalkyl methacrylate, which are excellent in oxygen permeability, have been widely used. However, when these materials are formed into contact lenses, the mechanical strength tends to deteriorate, and such contact lenses are likely to break when washed by the users.
The contact lenses include soft contact lenses other than the above-mentioned hard contact lenses. The soft contact lenses have merits such that they are soft and flexible and thus readily compatible with cornea, and thus they present comfortable feeling to wearers. Such soft contact lenses include substantially non-water absorptive contact lenses. However, most of usual soft-contact lenses are water-absorptive contact lenses which soften upon absorption of water. Such water-absorptive soft contact lenses are not so excellent in oxygen permeability and may sometimes hinder metabolism of cornea. Therefore, in recent years, there have been attempts to increase the water content of such soft contact lenses and thereby to improve the oxygen permeability. However, there is a problem that as the water content increases, the mechanical strength tends to decrease, and bacteria or the like tend to propagate readily in the material.
As materials to solve the above problem, there have been proposed a contact lens material made of a polymer obtained by polymerizing polymerizable components containing a bifunctional organosiloxane macromer as the main component (Japanese Unexamined Patent Publication No. 5861/1993), a fluorine-containing soft contact lens material obtained by copolymerizing a hydrophilic monomer, a methacrylic acid derivative and a fluorine-containing urethane dimethacrylate ester (Japanese Unexamined Patent Publication No. 130109/1992) and a contact lens material made of a copolymer obtained from a monomer mixture containing a siloxane oligomer as an essential component (pamphlet of International Publication No. 91/10155).
It is true that these materials are relatively superior to conventional materials in the oxygen permeability and mechanical strength such as impact resistance, and the above-mentioned fluorine-containing soft contact lens material has deposit resistance to some extent. However, such physical properties are still not practically fully satisfactory, and it is desired to develop an ocular lens material which has superior oxygen permeability and high mechanical strength and which at the same time is excellent in deposit resistance.